Currently, the global annual production of municipal solid waste amounts to about 10 billion tons, among which the annual production of municipal solid waste in China amounts to 250 million tons and rapidly grows at a rate of 8% to 15% each year; and landfill is still a major method for disposal of municipal solid waste in most of the countries including China. There are 100,000 and 150,000 landfills in the U.S. and Europe respectively, and China has more than 20,000 landfills. The existence of a large number of landfills brings a huge risk of environmental disasters, among which groundwater pollution caused by leakage and breakthrough of landfill leachate from anti-seepage liners is one of the most common pollution disasters.
The breakthrough of leachate from anti-seepage liners actually refers to seepage of pollutants in the leachate from the bottom of the anti-seepage liners after a long time of migration and dispersion with permeation of the leachate. When the seepage concentration of the pollutants gradually increases and reaches the harm-causing or pollution-causing concentration, groundwater and surrounding environment will be polluted. Therefore, breakthrough time of anti-seepage liners in a landfill is crucial in environmental safety assessment of the landfill. However, a landfill system is rather complex, concerning factors such as the thickness of anti-seepage liners, the permeability coefficient of the liners, the leachate head of the landfill, and the porosity of the material of the liners, which bring a heavy load to design, management, subsequent repairing and other work of the landfill.